1. Field of the Invention
The present invention relates to an improved process and apparatus for performing endothermic catalytic reactions.
2. Description of the Prior Art
Applicant's U.S. application Ser. No. 738,831, filed June 21, 1968, now U.S. Pat. No. 3,785,953 relates generally to a process for performing endothermic catalytic reactions which consists basically of introducing the reaction stream into at least one catalysis zone, constituted by at least one zone containing a dilute catalyst and which can itself be preceded by a zone containing an inert catalyst-support, said dilute catalyst zone being followed by a conventional catalysis zone proper, each of said zones being also separable from adjacent zones by intercalated zones containing no material, and/or distributing along said zones, heating means capable of supplying variable amounts of heat to the reaction stream moving in each of said zones, the temperature within said stream being maintained substantially constant during its passage through said zones.
A process of this type is particularly advantageous in the catalytic reforming of petroleum fractions. According to an advantageous feature, the heating means are arranged outside the catalysis tubes, for example reforming furnace tubes, and they are constituted notably by radiant heating means whose heat flow can be directed on to several pipes. According to another preferred feature, the endothermicity of the reaction is controlled, thereby affecting at the same time the heating and the reactivity of the catalytic mass, the latter being adjusted by suitable dilution of the pure catalyst, adapted to the reaction capacity of the feedstock according to its degree of conversion.
It is thus possible to provide, between the inert inlet zone and the active outlet zone containing the 100% pure catalyst, successive catalyst zones whose ratio of dilution varies between 10 and 90%, with respect to the pure catalyst. For the dilution, provision is made for using preferably the inert catalyst-support, before its impregnation by the catalytically active chemical species.
By means of the process of the aforementioned patent, throughout a reactor comprising a group of catalysis tubes, a temperature profile is obtained related to that of an isotherm.